Structure of the PLP degradative enzyme 2-methyl-3-hydroxypyridine-5-carboxylic acid oxygenase from Mesorhizobium loti MAFF303099 and its mechanistic implications.

Publication Type:

Journal Article

Authors:

McCulloch, Kathryn M; Mukherjee, Tathagata; Begley, Tadhg P; Ealick, Steven E

Source:

Biochemistry, Volume 48, Issue 19, p.4139-49 (2009)

Keywords:

Alphaproteobacteria, Binding Sites, Catalysis, Cloning, Molecular, Crystallography, X-Ray, Dimerization, Escherichia coli, Flavin-Adenine Dinucleotide, Histidine, Hydrogen Bonding, Ligands, Mixed Function Oxygenases, Models, Molecular, Nicotinic Acids, Oxidation-Reduction, Protein Binding, Protein Structure, Secondary, Recombinant Proteins, Substrate Specificity, Ultracentrifugation

Abstract:

<p>A vitamin B(6) degradative pathway has recently been identified and characterized in Mesorhizobium loti MAFF303099. One of the enzymes on this pathway, 2-methyl-3-hydroxypyridine-5-carboxylic acid oxygenase (MHPCO), is a flavin-dependent enzyme and catalyzes the oxidative ring-opening of 2-methyl-3-hydroxypyridine-5-carboxylic acid to form E-2-(acetamino-methylene)succinate. The gene for this enzyme has been cloned, and the corresponding protein has been overexpressed in Escherichia coli and purified. The crystal structure of MHPCO has been solved to 2.1 A using SAD phasing with and without the substrate MHPC bound. These crystal structures provide insight into the reaction mechanism and suggest roles for active site residues in the catalysis of a novel oxidative ring-opening reaction.</p>